PLA coated Paper User Guide

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Core Differences Between PLA& PE Coating:

Detailed Guide for Each Process:

1. Temperature Control Management: the Core Difference

 ＊PE Coated Paper Cups:

Wide temperature resistance, allowing for certain temperature fluctuations during heat sealing, and a high tolerance for errors.

 ＊PLA Coated Paper Cups:

① "Precise low-temperature control" is crucial. Excessively high temperatures will cause PLA to rapidly degrade, becoming brittle, yellowing, and losing its adhesive properties. Excessively low temperatures will prevent it from melting, resulting in a weak seal between the cup base and the hem, and possible leakage.

②Targeted Adjustments Required: The paper cup machine's heat-sealing mold temperature, hem wheel temperature, and preheating device all need to be adjusted downward to find the optimal "sweet spot" for PLA. This requires repeated adjustments.

2. Cooling System: Determines Cup Stiffness

＊PE Coated Paper Cups:

PE is relatively easy to cool from a molten state and set, so conventional cooling systems are sufficient.

＊PLA Coated Paper Cups:

① PLA crystallizes more slowly, requiring stronger and more aggressive cooling.

②Enhanced Cooling Required: Adding a cooling fan or adjusting the cooling duct may be necessary to ensure the cup body and base cool quickly after forming. If cooling is insufficient, the cup edge will rebound and deform, and the cup body will feel soft and weak.

3. Mold and Machine Setup: Addressing Material Characteristics

＊PE Coated Paper Cups:

PE is tough, requiring wider mold design tolerances.

＊PLA Coated Paper Cups:

① More Precision Molds: Because PLA is harder and more brittle, molds (especially the hem and base molds) require smoother, more precise construction to reduce friction and stress concentration, preventing cracks or burrs during production.

② Adjusting Pressure and Speed:

 Pressure: The hem and base seal pressure may need to be reduced to avoid crushing the PLA coating.

 Speed: The machine speed may need to be slightly reduced to ensure adequate heat sealing and cooling time.

4. Environment and Storage: Moisture-Proofing is Key

＊PE Coated Paper:

Insensitive to ambient humidity.

＊PLA Coated Paper:

① PLA is hygroscopic. If the base paper is stored in a humid environment for too long, the PLA layer will absorb moisture.

② Hazards: When heated, the absorbed moisture will form bubbles, causing the coated layer to blister and peel, resulting in serious quality problems.

③ Solution: PLA base paper must be stored in a dry, cool environment and used promptly. Sealed aluminum foil bags are recommended.

Summary: Key Elements for Successful PLA Paper Cup Production

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To consistently produce high-quality PLA coated paper cups, keep the following four points in mind:

1. Precise temperature control is key: Systematically adjust the machine temperature to the lower temperature range required by PLA and ensure that temperature remains stable.

2. Enhanced cooling is essential: Upgrade or optimize the cooling system to ensure rapid PLA shaping and maintain cup stiffness.

3. Mold and parameter adjustments are crucial: Patiently adjust the machine pressure, speed, and mold conditions to accommodate the hard and brittle characteristics of PLA.

4. Moisture-proof storage is essential: Ensure that the PLA base paper is dry before production.